Is it possible to get a Verizon iPhone 4 unlocked?

My friend is giving me her iPhone for free so I want to know if there's anyway I can get it unlocked to switch to my carrier.

That depends on your carrier. There are two types of cell towers CDMA (verizon, page-plus,) and GSM(att, t-mobile) all cell companies use one or the other. So a CDMA phone will never work on a GSM network and visa-versa. You can "flash" your friend's phone to work on like Page-Plus which is a low cost no-contract provider but it will be 3g only. Flashing is not easy and should be done by pros. Costs about $40 but the monthly savings will make it worthwhile